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Documentation/kbuild/makefiles.txt lists variables used in Makefile whereas Documentation/kbuild/kbuild.txt describes user assignable parameters given via environments or the command line. The top Makefile and arch/*/Makefile accumulate proper linker flags to LDFLAGS_vmlinux. So, users can not override it from the command line. Generally, per-file options are not supposed to be user-assignable. Remove the misleading entry from kbuild.txt. If we need a way to append user-specific flags for linking the kernel, LDFLAGS_KERNEL would be a consistent choice because we already expose LDFLAGS_MODULE counter-part to users. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
241 lines
8.3 KiB
Plaintext
241 lines
8.3 KiB
Plaintext
Output files
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modules.order
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--------------------------------------------------
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This file records the order in which modules appear in Makefiles. This
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is used by modprobe to deterministically resolve aliases that match
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multiple modules.
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modules.builtin
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--------------------------------------------------
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This file lists all modules that are built into the kernel. This is used
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by modprobe to not fail when trying to load something builtin.
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Environment variables
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KCPPFLAGS
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--------------------------------------------------
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Additional options to pass when preprocessing. The preprocessing options
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will be used in all cases where kbuild does preprocessing including
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building C files and assembler files.
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KAFLAGS
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--------------------------------------------------
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Additional options to the assembler (for built-in and modules).
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AFLAGS_MODULE
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--------------------------------------------------
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Additional module specific options to use for $(AS).
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AFLAGS_KERNEL
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--------------------------------------------------
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Additional options for $(AS) when used for assembler
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code for code that is compiled as built-in.
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KCFLAGS
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--------------------------------------------------
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Additional options to the C compiler (for built-in and modules).
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CFLAGS_KERNEL
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--------------------------------------------------
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Additional options for $(CC) when used to compile
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code that is compiled as built-in.
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CFLAGS_MODULE
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--------------------------------------------------
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Additional module specific options to use for $(CC).
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LDFLAGS_MODULE
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--------------------------------------------------
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Additional options used for $(LD) when linking modules.
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KBUILD_VERBOSE
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--------------------------------------------------
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Set the kbuild verbosity. Can be assigned same values as "V=...".
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See make help for the full list.
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Setting "V=..." takes precedence over KBUILD_VERBOSE.
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KBUILD_EXTMOD
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--------------------------------------------------
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Set the directory to look for the kernel source when building external
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modules.
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The directory can be specified in several ways:
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1) Use "M=..." on the command line
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2) Environment variable KBUILD_EXTMOD
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3) Environment variable SUBDIRS
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The possibilities are listed in the order they take precedence.
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Using "M=..." will always override the others.
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KBUILD_OUTPUT
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--------------------------------------------------
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Specify the output directory when building the kernel.
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The output directory can also be specified using "O=...".
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Setting "O=..." takes precedence over KBUILD_OUTPUT.
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KBUILD_DEBARCH
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--------------------------------------------------
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For the deb-pkg target, allows overriding the normal heuristics deployed by
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deb-pkg. Normally deb-pkg attempts to guess the right architecture based on
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the UTS_MACHINE variable, and on some architectures also the kernel config.
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The value of KBUILD_DEBARCH is assumed (not checked) to be a valid Debian
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architecture.
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ARCH
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--------------------------------------------------
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Set ARCH to the architecture to be built.
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In most cases the name of the architecture is the same as the
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directory name found in the arch/ directory.
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But some architectures such as x86 and sparc have aliases.
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x86: i386 for 32 bit, x86_64 for 64 bit
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sparc: sparc for 32 bit, sparc64 for 64 bit
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CROSS_COMPILE
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--------------------------------------------------
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Specify an optional fixed part of the binutils filename.
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CROSS_COMPILE can be a part of the filename or the full path.
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CROSS_COMPILE is also used for ccache in some setups.
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CF
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--------------------------------------------------
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Additional options for sparse.
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CF is often used on the command-line like this:
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make CF=-Wbitwise C=2
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INSTALL_PATH
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--------------------------------------------------
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INSTALL_PATH specifies where to place the updated kernel and system map
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images. Default is /boot, but you can set it to other values.
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INSTALLKERNEL
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--------------------------------------------------
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Install script called when using "make install".
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The default name is "installkernel".
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The script will be called with the following arguments:
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$1 - kernel version
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$2 - kernel image file
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$3 - kernel map file
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$4 - default install path (use root directory if blank)
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The implementation of "make install" is architecture specific
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and it may differ from the above.
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INSTALLKERNEL is provided to enable the possibility to
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specify a custom installer when cross compiling a kernel.
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MODLIB
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--------------------------------------------------
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Specify where to install modules.
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The default value is:
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$(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
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The value can be overridden in which case the default value is ignored.
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INSTALL_MOD_PATH
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--------------------------------------------------
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INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
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relocations required by build roots. This is not defined in the
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makefile but the argument can be passed to make if needed.
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INSTALL_MOD_STRIP
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--------------------------------------------------
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INSTALL_MOD_STRIP, if defined, will cause modules to be
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stripped after they are installed. If INSTALL_MOD_STRIP is '1', then
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the default option --strip-debug will be used. Otherwise,
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INSTALL_MOD_STRIP value will be used as the options to the strip command.
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INSTALL_FW_PATH
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--------------------------------------------------
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INSTALL_FW_PATH specifies where to install the firmware blobs.
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The default value is:
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$(INSTALL_MOD_PATH)/lib/firmware
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The value can be overridden in which case the default value is ignored.
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INSTALL_HDR_PATH
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--------------------------------------------------
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INSTALL_HDR_PATH specifies where to install user space headers when
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executing "make headers_*".
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The default value is:
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$(objtree)/usr
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$(objtree) is the directory where output files are saved.
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The output directory is often set using "O=..." on the commandline.
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The value can be overridden in which case the default value is ignored.
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KBUILD_SIGN_PIN
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--------------------------------------------------
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This variable allows a passphrase or PIN to be passed to the sign-file
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utility when signing kernel modules, if the private key requires such.
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KBUILD_MODPOST_WARN
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--------------------------------------------------
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KBUILD_MODPOST_WARN can be set to avoid errors in case of undefined
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symbols in the final module linking stage. It changes such errors
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into warnings.
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KBUILD_MODPOST_NOFINAL
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--------------------------------------------------
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KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
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This is solely useful to speed up test compiles.
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KBUILD_EXTRA_SYMBOLS
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--------------------------------------------------
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For modules that use symbols from other modules.
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See more details in modules.txt.
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ALLSOURCE_ARCHS
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--------------------------------------------------
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For tags/TAGS/cscope targets, you can specify more than one arch
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to be included in the databases, separated by blank space. E.g.:
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$ make ALLSOURCE_ARCHS="x86 mips arm" tags
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To get all available archs you can also specify all. E.g.:
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$ make ALLSOURCE_ARCHS=all tags
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KBUILD_ENABLE_EXTRA_GCC_CHECKS
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--------------------------------------------------
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If enabled over the make command line with "W=1", it turns on additional
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gcc -W... options for more extensive build-time checking.
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KBUILD_BUILD_TIMESTAMP
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--------------------------------------------------
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Setting this to a date string overrides the timestamp used in the
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UTS_VERSION definition (uname -v in the running kernel). The value has to
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be a string that can be passed to date -d. The default value
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is the output of the date command at one point during build.
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KBUILD_BUILD_USER, KBUILD_BUILD_HOST
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--------------------------------------------------
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These two variables allow to override the user@host string displayed during
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boot and in /proc/version. The default value is the output of the commands
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whoami and host, respectively.
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KBUILD_LDS
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--------------------------------------------------
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The linker script with full path. Assigned by the top-level Makefile.
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KBUILD_VMLINUX_INIT
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--------------------------------------------------
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All object files for the init (first) part of vmlinux.
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Files specified with KBUILD_VMLINUX_INIT are linked first.
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KBUILD_VMLINUX_MAIN
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--------------------------------------------------
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All object files for the main part of vmlinux.
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KBUILD_VMLINUX_LIBS
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--------------------------------------------------
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All .a "lib" files for vmlinux.
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KBUILD_VMLINUX_INIT, KBUILD_VMLINUX_MAIN, and KBUILD_VMLINUX_LIBS together
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specify all the object files used to link vmlinux.
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